The present invention is related to a paint dosage device for use in spray painting installation, a program controlled The paint dosage device provides for a dosed paint supply to the applicator or spray gun, and in particular for the case in which the applicator is provided with high tension electrode for electrical atomizing of the supplied electrically conductive paint. In addition the paint dosing apparatus must also be well insulated, explosion-proof and reliable, without being excessively difficult or expensive to implement. Application with direct charge of conductive or water borne paints requires an effective insulation or galvanic blocking between a spray gun/applicator charged with a high voltage and apparatus at zero or ground potential, in particular a paint dosing device and/or the paint lines supplying the dosing device.
U.S. Pat. No. 5,630,552, (Anfindsen) entitled Paint dosage device for program controlled spray painting system, describes a spray painting installation particularly suitable for the application of electrostatically atomized paint. The dosage device of the installation comprises dosing cylinders. Each dosage cylinder has a regulating piston, respectively, and regulation members for controlling the position and displacement velocity of the regulating pistons in the dosing cylinders. The dosing cylinders also have a controlled valve assembly and connection means for connecting the cylinders alternately to the spray gun and for connecting the cylinder when disconnected from the gun in connection with means for cleansing and refilling of paint. The dosage device described may be mounted in close proximity to a spray gun on a robot arm, it provides accurate dosing of fluid materials (paint) and it is insulated from the paint supply lines.
An international patent application WO IB2004/003104 (Anfindsen et al), assigned to ABB, which is hereby incorporated in full by means of this reference, describes an improved spray painting system with a dosing device. In particular it describes means for achieving a galvanic block, or voltage block, between the dosed fluid in contact with a high voltage and the fluid in the supply lines or paint kitchen etc which is normally at ground potential. In this description a dosing device is described which comprises one or more dosing cylinders which may be filled at a paint supply point, moved away from the supply point and towards a spray head connection point, and there connected to one or more spray heads. An insulation cover is described which is arranged surrounding a docking head in the region of the connection point between the valve block for the spray head and a dosing cylinder. The cover is arranged such that as a dosing device is moved forward into the housing a galvanic contact is made by a charging antennae which may be a single electrode, scraper or a brush, before the valves of the dosing device make contact with the valves of the docking head.